FIG. 1 shows a distributed network. The network comprises a number of devices 1. Each device can communicate wirelessly with the other devices that are in effective range of it. In this example the network is a mesh network. The devices can cooperate to propagate signals between them. For example, if device 1a transmits a signal, that signal can be received by devices 1b and 1c which are within range of device 1a. Devices 1b and 1c can then relay the signal received from device 1a so that it can be received by device 1d which is out of range of device 1a. This method of communication allows devices to communicate even though they are out of direct range of each other.
FIG. 1 shows a further device 1e which is out of wireless range of ail the devices 1a to 1d. In a basic mesh network none of the devices 1a to 1d can communicate with device 1e using the mesh protocol. However, they may be able to communicate with device 1e using some other protocol. For example, devices 1a and 1e might be connected to a wired network as illustrated at 2, and that pair of devices may be able to communicate over that wired network. The wired network might be expected to use a different protocol from the wireless protocol. A consequence of that may be that device 1a cannot simply forward messages of the mesh protocol to device 1e, which can make communications with device 1e inconvenient.
It may be possible to impose the same protocol on the wired network and the wireless mesh network. However, the inherent differences in the capabilities of those networks mean that imposing the same protocol would be expected to reduce performance. For example, the mesh network might be expect to involve greater latency, higher numbers of retransmissions and a greater level of interference than the wired network. Therefore, it might be desirable to have different message lengths, retransmission protocols and addressing protocols, among other distinctions, as between the different networks. Those differences lead to the difficulties of intercommunication discussed above.
There is a need for an improved way of communicating between devices in a mesh network and devices that are external to the mesh.